Any idea what could be causing the following error when I spin off a new parent image?

"Task message:

Create failed. Copy operation for "KUVDIimgW7d-20120312005725.vhd" failed! The system cannot find the file specified"

I've removed all reference to this disk and tried re-importing. This master image has been working fine until last night. Only changed I made was booting it up and copying over a txt fille....

Dan